# What are the units of electricity? ## What is a megawatt MW, megawatt-hour MWh, kilowatt kW and kilowatt-hour kWh?

Let’s learn how electricity is measured! Get to know what are the units of electricity!

When one first starts looking into electricity, you become bombarded with terms that can become confusing. However, they are relatively easy to understand, and we can go through them all quickly here so you can get back to your solar or electrical research.

Let’s start at the beginning.

## What is a watt?

A watt is the basic unit of power.

P (watts)= Voltage (V) x Current (I)

It is a measurement of the amount of electrical energy in a circuit and the amount of electrical work the circuit can perform.
1000 watts equals a kilowatt.
A megawatt is just 1,000,000 or 1 million watts of power, as the name implies.

A gigawatt is 1,000,0000,000 or 1 billion watts of power.

## Why do we need Mwh and Kwh?

As society electricity is a commodity. Electricity generators supply the commodity and households and businesses consume the commodity.

There was traditionally always a marginal cost of generating electrical energy (long before renewables), and so it became necessary to measure the exact amount of electrical energy that was supplied or used over periods of time.

### What is a kilowatt-hour (kWh)?

A kilowatt-hour is a measure of the total use of electrical energy over a time period and is equivalent to 1000 watts of power (a kilowatt) being used continuously for 1 hour.

So a one-kilowatt hour could be someone using 1000 watts for an hour, or it could be someone using 10,000 watts for 6 minutes (0.1 of an hour). Either way, they have used 1 kilowatt-hour of electrical energy.

### What is a megawatt-hour (MWh)?

A megawatt hour is equivalent to 1 million watts of electricity being used for an hour. 1 MWh is equivalent to 1,000 kWhs.

A megawatt hour could be 2 million watts (2 megawatts) of power being used for half an hour or it could be 500 kW (.5 megawatts) of power being used continuously for 2 hours.

## Why are solar systems sold in kilowatts?

When solar panels are marketed in kilowatts, it signifies that the peak DC capacity of all the solar panels adds up to that number.

As a result, a 5 kW system made up of 20 x 250-watt solar panels will be offered.
However, this does not imply that it will produce 5 kW of instantaneous power or 5 kWh of power in an hour.
When you check at your solar system’s inverter or monitoring, you’ll notice that the real-world output of solar panels is rarely near its peak capacity. The actual production is affected by sun irradiation, system design losses, and perhaps dirt or shade. Knowing what are the units of electricity, it’s not hard to understand now that solar systems are sold in kilowatts (kW).

## How many kilowatt-hours of power are produced by each kilowatt of solar panels?

The amount of power generated by each peak kW of solar panels varies around the country.